This shield mates with Smoothieboard and makes it easy to connect a parallel port style CNC machine such as is commonly used with LinuxCNC or Mach3. It also has connectors to allow easy connection of a Reprap Discount Graphic LCD Screen. The Parallel Shield has integrated level shifters that boost Smoothieboard's 3.3V logic up to 5V for the Parallel port (as well as the GLCD logic while we're at it) to help make sure that even older CNC machines and electrically "noisy" shop environments do not have communication problems.
It can either be powered by your Smoothieboard's 5V line or it can power itself with an on-board 5V 500mA Switching Regulator that pulls from Smoothieboard's VBB line. Be aware that USB only supplies 500mA of power. This is enough for Smoothieboard or a GLCD screen but not both. In order to overcome this and power the on-board regulator on the Parallel Shield you will need to connect 12V - 24V to Smoothieboard's VBB line even if you are not using the built in stepper drivers.
Documentation on connecting a display panel to your Smoothieboard can be found on the Smoothie Project wiki here: http://smoothieware.org/panel
This is one of the first Uberclock pcbs designed in Kicad, along with the Smoothieboard GLCD Shield. Go team open source! As always, the source files are available on github: https://github.com/logxen/SmoothieboardParallelShield